By virtue of the progress in information communication networks and the like such as the Internet in these few years, each user can now easily access network information through individual-oriented terminals employing a cellular phone or the like.
In such information communication, information is transmitted through digital signals. It is now possible to obtain copied audio data and image data transmitted via the aforementioned information communication network without almost no degradation in the audio quality and picture quality of the copied data, even in the case where the copy operation is performed by an individual user.
Thus, there is a possibility of the copyright of the copyright owner being significantly infringed unless some appropriate measures to protect copyrights are taken in the case where any created work subject to copyright protection such as audio data and image data is to be transmitted on such an information communication network.
However, if copyright protection is given top priority so that distribution of copyrighted data through the disseminating digital information communication network is suppressed, the copyright owner who can essentially collect a predetermined copyright royalty for copies of a copyrighted work will also incur some disbenefit.
In the case where copyrighted data such as audio data is distributed through the above-described digital information communication network, each user will reproduce the distributed data using a reproduction apparatus after the distributed data is recorded on some recording device.
Such a recording device includes, for example, a medium that allows data to be written and erased electrically such as a memory card.
As the apparatus to reproduce the distributed data, the cellular phone per se used to receive data distribution can be employed. Alternatively, in the case where the recording device is detachable from the apparatus that receives distribution such as a memory card, a dedicated reproduction apparatus can be used.
In such a case, some security measures must be taken at the recording medium side in order to protect the rights of the copyright owner so that content data (audio data or the like) received by distribution cannot be transferred illegally to another record medium without the permission of the copyright owner.
Furthermore, protection on the rights of the copyright owner and the proper user will be impaired if one other than the user who has received content data distribution by appropriately paying the proper price can freely read out the content data at the reproduction apparatus side during the reproduction of audio data and the like from the recording medium.